I plan on getting my corney keg filled up at a local microbrewery and they told me to make sure it was clean (check), sanitized (check), and pressurized (Not Checked). I understand what they mean by pressurized, but a little unsure of the procedure. My common sense tells me to put the lid on the keg and pump up for CO2 to around 30 PSI until I no longer hear the gas flowing...check for any leaks and then thats it. Does the sound right?

--- End quote ---I would think it's because you want the keg to stay sealed. Sometimes if there isn't enough pressure, the gaskets won't seat, and you'll have a leak. Obviously 30 psi is more than enough to get your keg sealed, however, If there is a big change in temperature it can greatly change the pressure inside the keg. The brewery has to allow pressure out of the keg while filling it or else it might blow!